MANILA, Philippines -- Philippine Long Distance Telephone Co. has filed a suit in a U.S. district court against parent First Pacific Co. for alleged violation of disclosure rules in an apparent move to further obstruct the planned sale of a controlling stake in PLDT to a group led by local businessman John Gokongwei.

In a statement Thursday, PLDT said the complaint was filed with a district court in New York on July 3. In its complaint, PLDT told the court that First Pacific's failure to submit a copy of the memorandum of...